3. Exfoliation or flaking of rocks due to expansion in extremely high daytime temperatures with contraction in extremely low nighttime temperatures is a form of:A erosionB physical weatheringC chemical weathering

5. Water can break down rocks because:A water carries strong acids that erode rocksB water takes up less space when it freezes and rocks collapse inwardC water expands when it freezes in cracks in rocks

6. City council regulations ban the planting of certain trees near buildings because:A tree roots can damage and break down concreteB the tree sap is poisonous to humansC trees create shade and the temperature extremes can break concrete

7. An example of physical weathering by animals is when:A insects damage flowers when they are obtaining nectarB tree roots break up concrete slabsC people walk on grass instead of the designated paths

8. What weathering chemicals are made by decaying plants?A alkalisB acidsC salts

9. What is formed when gases such as carbon dioxide, sulphur dioxide and nitrogen oxides mix with rain?AerosionBacid rainClichens